Filtering apparatus



July 25, '1939.1 am ET AL 2,167,322 FILTERING APPARATUS Filed Julylv, V1936 r2 sheets-sheet 1 Moro/2 .OR/ VEN Pif/MP Julyv25,1939. ACQH.cumofmm. k` 2,167,322

1 FILTERING'y MPARATUS` l v Filed July 17, l193,6 f ashets-sheet 2y g5 readily cleaned.

" Patented July 25, 1939 I r y UmTE-DA STATES PATENT N ori-ICE FILTERING APPARATUS Charles H. Cuno and Sidney L. Wolfson, Meriden,

Conn., assignors to The Cuno Engineering Corporation, Meriden, Conn., a corporation of Conv necticut YApplication July i7; 1936, Serial No. 91,034 s Claims. (014210-467) Our invention relates to apparatus particularl in the form of a thin stream against the inside intended for the filtering of liquids. v of the filtering area so as to force collected residue One object is to provide a construction which outwardly from between the adjacent wires as is rugged and dependable. the-cage rotates. The pressure of this backwash 5 4Another object is to provide a construction flow may be varied by 'controllingapump or other 5 which makes it possible to have extremely iine or means for forcing the filtered liquid back into the small openings. inlet end of the iilter so that no liquid is lost. Another object is to provide a practical and Fig. 1 is a side view and partial section of one reliable construction which can be readily made form of apparatus embodying our invention.

1o according to standard specifications. I Y Fig. 2 is a vtransverse sectional View of a iilter l0- Another 'object is 'to provide a construction unit on a somewhat larger scale than the drawwhich can be made up in various sizes. A ing ofFig. 1. Another object is to provide a construction Fig. 3 is a View 'showing a fragment of the which is capable yof embodiment in very large filtering element or unit. l5 sizes. Fig. 4 is 'a longitudinal sectional view of a l5 Another object is to provide aconstructionin filtering unit composed of three sections. which the filtering member may comprise one or Fig. 5 is a side view and partial section -showmore similar units enabling its length to be ar- Aing filtering apparatus embodying a numberof ranged to vsuit the requirements of various cases the units shownin Fig. 4 buton a smaller scale. 20 while employing one standardized unit with at- Figs. 6 and `'7 show fragments of other forms l0 tendant economles'in castings. patterns, machinof ltering media ing, assembly, etc. Y The head casting' I3 of the filter is boltedto Another object is toprovide a `construction in the ring I 4 which forms one end of and is supwhich the filtering or straining surfaces can Abe ported by the circumferential cylindrical wall of FT the casing. The header'lts the closer I6 which 26 Another object is to provide a construction in vcommunicates with the outlet I2 at the 'other end which the filteringk or straining surfaces can be of the casing. The bolts Il .connect the head I3 cleaned by backwashing without the necessity of and the header I5 and space theml at the proper providing. a separate source for, or wastage of.v distance.

`3.0 the backwashliquld. Between the members I3 and I5 is rotatably 80 In commercial practice it has been common to mounted the filtering unit I8 whose shaft I9 ifas make up filters according to fo'urj'general plans. suitable bearings in the head members I3 and I5. One, those embodying the use of filtering sub- `In the form shown the iiltering cylinder or cage .stances such as sand or'other iinely divided iln- I8 has a number of wedge shaped bars 20 which 35 organic material. Another utilizing fibrous maare carried by rings 2| and 22 at opposite ends. 85

terial in mass 'or in fabric form. Another The spider 23 is keyed to the shaft I9,bolted to utilizing a multiplicityv of -plates which are athe rring 22 and rotates in the header I5. The ranged with spaces between adjacent plates spaces 24 between 'the adjacent bars Ziiare prefthrough which the liquid passes, and a fourth erably wedge shaped. The wire 25 is wound o -type in which wire is employed to form the strainhelically upon the bars 20 being located in shal- 40,

ing or filtering area. low grooves 26 in the bars 20.. This wire may be Each of these forms has a considerable field either of round or flattened cross section and is of utility but noneof them44 is thoroughly satiswound from end to end on the filtering cylinder. factory for iilters of large size. According to our The wire may be made -very fine and the spac- A4'5" iri vention we provide a skeleton-like cage upon ing 21 regulated by the grooving or notchng of 45 which is wound a length of wire in helical form. the bars 2Il. In case ,the wire is flattened at The liquid passes through this cage from the outintervals as shown in Fig. 6 the grooves are uuside to the inside from whence itis discharged. necessary. The Spider member I3 has passages vThis cage with the wire helix constitutes the 28, the ring member 23 has passass `and the ,d ii-lterlng Aunit'and is rotated as a part of the header I5 hasra :lumber of passages .30 so'that 50` cleaning operation. Arelatively stationary blade liquid whichpasses between the wires into the is. located outside of the filtering unit for reinterior 'of the filter cylinder passes out to the moving the projecting residue from the outside. charge outlet I2. The solids are, of course, de-

Inside of the filtering unit is located an elon-V posited on the outside of the cylinder element I8. gatednozzle from which filtered liquid is forced The filtering unit is preferably rotated auton 5.?,

matlcally for instance by means of an electric motor 3| and a gear train 32' connected to the shaft I9.

A scraper blade is mounted on the rod I1 and is preferably pressed by a spring 36 toward the wire 25 so as to scrape olf any material from the outside as the ltering element rotates. Preferably there are a number of these scraper blades as shown in Fig. 2 arranged at intervals around the periphery of the cylinder.

`The motor driven pump draws filtered liquid through the pipe BI and forces it through the pipe 42 and passage 43 into a conduit 45 which empties through an opening into an elongated nozzle having an outlet 41 arranged in proximity to the inner edges of the bars 2li. This conduit B5 and the nozzle 41 are secured to and supported at opposite ends by the head I3 and the spider I3'.-

The spider I3 is supported but does not rotate on the shaft I9 inside the ring 22 and is also connected to the head I3 by bolts M. By this construction a thin stream of liquid may be forced outwardly between the bars 20 and' through the spaces 21 between adjacent helices of the wire screen. Thus-concentrated spurts or streams of liquid force any `material outwardly from the spaces in the cylinder wall so that much of the material will` fall down into the casing and the z tween the inlet 5I balance of it willv be scraped off by the action of the blades 35 as the screen rotates.

This backwash fiow. of course, is at a greater pressure and in a direction contrary to the flow of the liquid which is being filtered but it occurs at only a very small part of the filtering area. In

the form shown for instance there are forty of the passages 2t and the nozzle outlet 41 is so narrow that it never acts on more than one out of the forty passages at a time. Although this is a preferred arrangement it should be understood that the invention is not limited to this specic proportion as the discharge stream might Aact upon two or more of the passages simultaneously.

, In order to adjust or vary the backwash ow and pressure we provide a bypass 48 extending from the outlet end of the filtering apparatus around the motor driven pump 40 and connected to the conduit 42 between the pumpand the inlet 43 to the baci-:wash nozzle. This bypass is controlled by a valve 49 by adjustment of which the backwash pressure may be varied.

In the form shown in Fig. 5 the lter casing 50 has an inlet 5I and an outlet 52. A number of alter umts 53 such as shown in Fig. 4 are em' ployed. A baiile plate 54 may be interposed beand the adjacent filtering elements.

AIn this form each filter unit has a top plate 55 and a bottom or base plate 56 with connecting rods 51 (which correspond with bolts I1).

lil)

The rotatable shaft 58 carries a series of filtering sections 60, 6I and 62', each of which is similar to the filtering unit previously. described. Each lter section has an outer periphery 63 of wire.` Theliquid to be filtered passes inwardly through 'l the filtering areas and is discharged from the bottom of the unit through the header 56.

etc. (not shown) 66 and 61 may be gradually reduced in cross section to correspond' with the diminished volume of liquid to pass through. y

The liquid for the backwash is pumped from the t 'a sump 16 to collect the residue. Theupper endy of the apparatus is enclosed by a hood 'l1 inside of which is mounted the .necessary motors, pumps,

ber 18 may be provided, rotated by .some element within the 'casing to show when the apparatus is operating. j

This form of apparatus hasthe great advantage that it maybe made in very large sizes and still retain rigidity and long life.` It will be noted that the cleaning of the apparatus is carried on continuously and that there are lno parts to become permanently clogged. The parts are all of long life and the apparatus is capable of being made of any capacity desired. v

It will be seen that the cleaning is accomplished by clean liquid and without a loss of liquid and without the necessity of any separate supply or different kind .of backwash liquid. Extremely fine spacing of the filtering wire is possibleand this spacing can be readily varied in` small increments to suit requirements without special expense or equipment. The backwash ow and pressure can be varied to. suit any requirement by simple external bypass adjustments which need not interfere with the operation of the apparatus. very large diameter without prohibitive expense or complication in construction. 1

Although we prefer to employ a coil of wire as the filtering area, itshould be understood'that certain advantages of the invention may be obtained bythe use of a. corrugated, Vutedor perforated cylinder, a fragmentof which is shown in Fig. 7. l'

1. Liquid filtering apparatus including a casing witha cylindrical filtering cage insidethe casing and completely immersed -in liquid therein, means for forcing liquid to be filtered inwardly through said cage and means for forcing a relatively small backwash stream of the filtered liquid outwardly at a greater pressure through a part of the cage while liquid is being'forced inwardly for filtering and means for moving the cage relative to the backwash stream.

2. A filter comprising stationaryheads spaced apart from each other, acasing having one end secured to one head and the other end surrounding' the 'other head. a rotatable shaft having bearings in said heads, the casing having an inlet, a screen rotatably supported by said heads and said shaft, a backwash nozzle secured to one An ,external indicating mem- The elements may be made of head within the'screen, a stationary spider surthrough the latter head into the closer, a discharge pipe leading from the closer, a pump and conduit for withdrawing a part only of the fil-y tered liquid from the discharge pipe and forcing it through the inlet to the nozzle vunder greater pressure than thehead of the liquid outside of the screen to clear out material from the outside of the screen by the action of 'the liquid forced from thenozzle through the screen as the screen rotates. y K

3. A filter comprising stationary heads spaced apart from each other, a casing having one end secured to one head and the other end surrounding the other head, a rotatable shaft having bearings in said heads, the casing having an inlet, a screen rotatably supported by said heads and said shaft, a backwash nozzle secured to one head.

within the screen, an inlet throughthe rst menl tioned head to the nozzle, a closer for the other head, an outlet from the inside of the screen through the latter head into the closer, a discharge pipeleading from the closer, a pump and conduit for withdrawing a part only of the nl tered liquid from the discharge pipe and forcing it through'the inlet to the nozzle and scraping means carried by the heads within the casing and coacting with the outer surface of the screen to remove material loosened by the action ofthe liquid forced from the nozzle through the screen 

